Video Encoding Bit Rate Oscillation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video encoding technologies experience bit-rate oscillations, leading to undesirable artifacts and latency in video telephony, as they struggle to maintain a constant bit rate and short latency simultaneously, especially in real-time video encoding and transmission.
Innovation Solution
A method that dynamically adjusts quantization parameters (QP) for each macro block within a video frame, using a two-pass encoding scheme with multiple QP values to control bit rate, allowing for the merging of bit streams to achieve a stable bit budget, thereby reducing bit-rate oscillations and enabling early transmission of encoded macro blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a buffer is introduced in the receiver to compensate for bit-rate oscillations, then bit-rate stability is improved, but latency increases
Solution Approach 1:
The patent performs preliminary encoding passes to estimate bit rates and adjust QP values before final encoding. By predicting and compensating for bit-rate variations in advance through multiple passes, the system achieves bit-rate stability without requiring receiver-side buffering, thus avoiding latency.
2Productivity
If dynamic QP adjustment is used to control bit rate, then bit-rate control is improved, but bit-rate oscillations increase
Solution Approach 1:
The patent implements feedback mechanisms where the bit rate of previously encoded frames is measured and used to adjust QP values for subsequent frames. This closed-loop control ensures that dynamic QP adjustment maintains bit-rate control while preventing oscillations by continuously adapting to actual encoding results.
Solution Approach 2:
The patent uses periodic multi-pass encoding schemes where QP values are adjusted in regular intervals based on accumulated bit-rate measurements. This periodic adjustment smooths out short-term fluctuations and prevents bit-rate oscillations while maintaining overall bit-rate control.
3Stability of the object's composition
If multi-pass video encoding is used to reduce bit-rate oscillations, then bit-rate stability is improved, but latency increases
Solution Approach 1:
The patent applies different encoding strategies to different regions or portions of the video stream. By performing lightweight QP adjustments in early passes and refining only critical segments in subsequent passes, the system achieves bit-rate stability with minimal processing delay, reducing latency compared to full multi-pass encoding.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for encoding a video sequence of video frames. Each video frame includes a plurality of macro blocks. One video frame of the video sequence is encoded based on a first quantization parameter value for generating a first bit stream of encoded macro blocks (12). Transmission of a subset of the encoded macro blocks from the first bit stream is initiated (13). It is determined if the first bit stream exceeds a bit budget. If the first bit stream is determined to exceed the bit budget, a second quantization parameter value, which is larger than the first quantization parameter value, is generated. Otherwise, the second quantization parameter value, which is smaller than the first quantization parameter value, is generated. At least a part of the video frame is encoded based on the second quantization parameter value for generating a second bit stream of encoded macro blocks (15, 15a). The first bit stream and the second bit stream are then merged (17, 17a). An apparatus for performing the method is also disclosed.